Sodium sulfite

About: Sodium sulfite is a(n) research topic. Over the lifetime, 2548 publication(s) have been published within this topic receiving 18523 citation(s). The topic is also known as: Na2SO3 & Anhydrous sodium sulfite.

Adsorption kinetics and thermodynamic parameters of cationic dyes from aqueous solutions by using a new strong cation-exchange resin.

Abstract: Poly(glycidylmethacrylate) was grafted via surface-initiated-atom transfer radical polymerization (SI-ATRP) on a cross-linked acrylate based resin. Epoxy groups of the grafted polymer, were modified into strong cation-exchange groups (i.e., sulfonic groups) in the presence of sodium sulfite. The adsorption of Crystal Violet and Basic Fuchsine on the strong cation-exchange resin was studied under different experimental conditions. The adsorption process for both basic dyes was pH dependent. The maximum adsorption was observed for both dyes between pH 2.0 and 7.0. The maximum adsorption capacity of the cation-exchange resin for CV and BF dyes were found to be 76.8 and 127.0 mg/g, respectively. Adsorption of the dyes on the resin fitted to Langmuir and Temkin isotherm models and followed the pseudo-second-order kinetics. The values of Gibbs free energy of adsorption (Δ G °) were found to be −2.92 and −6.31 kJ/mol at 308 K for CV and BF dyes, respectively. These negative values indicated the spontaneity of the adsorption of the dyes on the resin. Desorption of both dyes was achieved from the resin by using 0.1 M HNO 3 and desorption ratio up to 97% was obtained over seven adsorption/desorption cycles.

Electrochemical capacitor of magnetite in aqueous electrolytes

Abstract: The capacitive behaviours of magnetite nanocrystallites, along with conductive carbon black additive, in aqueous electrolytes, including sodium sulphite, sulphate, chloride, and phosphate, and potassium hydroxide, have been characterised by means of cyclic voltammetry and chrono-potentiometry. The behaviour can be categorised into three groups. Sodium sulphate and chloride electrolytes give capacitances (∼5 F/g-Fe 3 O 4 ) close to the space-charge capacitance of the oxide. Potassium hydroxide and sodium phosphate gave rise to a higher capacitance (∼7 F/g) which can in part be attributed to a surface redox reaction which involves hydroxide ions. Sodium sulphite results in the highest capacitances, which depend heavily on the dispersion of magnetite crystallites on the conductive matrix and range from ∼30 to 510 F/g-Fe 3 O 4 with an operation voltage range of 1.2 V. Correlation between rest potential and anion-concentration gives strong indication of potential-determining process which involve either OH under extremely alkaline conditions (pOH 3 2− in the sulphite electrolyte.

Chlorination studies of free and combined amino acids

Abstract: Nitrogenous organic compounds in raw and treated water are of concern because they may exert high chlorine demand They are also known as precursors of halogenated compounds In this study, chlorine demand, TOX and THM formation potentials of 22 free amino acids, and some polypeptides and proteins were determined Results have shown that the reactivity of free amino acids with chlorine is related to their structure Experiments conducted with combined amino acids have shown that the amide linkage does not participate significantly in the chlorine demand of polypeptides, and does not seem to be TOX precursor Specific amino acids that possess reactive side groups such as amino nitrogen, sulfur or activated aromatic ring were defined as the main chlorine consumer and TOX precursor sites of polypeptides Complementary experiments indicated that sodium sulfite dechlorination can affect, more or less, the determination of amino acids TOXFP

Comparison of Protein Extraction Solutions for Rice Starch Isolation and Effects of Residual Protein Content on Starch Pasting Properties

Abstract: Protein extraction solutions such as aqueous solutions of sodium hydroxide (0.1 and 0.2 %), sodium lauryl sulfate (SLS, 1.2 %) containing sodium sulfite (0.12 %), and dodecylbenzene sulfonate (DoBS, 1.2 %) containing sodium sulfite (0.12 %) were compared in their protein removal efficiencies during isolation of starch from a rice flour (Ilpumbyo, a nonwaxy Korean rice variety). In addition, the pasting properties of the isolated starch was compared. More than 80 % of the flour protein was extracted in 1 h by stirring the dispersion (1:3, w/v) at room temperature. Repeating the extractions (1 or 2 h for each step) with fresh solution significantly increased the protein removal efficiency. When the extraction in 0.2 % NaOH was repeated four times (1 h for each step) at 25°C, the residual protein content in the isolated rice starch was 0.9 % (DB), equivalent to 86 % removal of the rice protein. Raising the extraction temperature slightly increased the protein solubility, but starch loss also became significant. Among the solutions, DoBS was most effective in removing rice protein whereas SLS was least. The residual protein content had a critical role in determining the pasting characteristics of the isolated starch, showing a negative correlation to the peak viscosity of the starch paste, but a positive correlation to the pasting temperature.

Stability of 5,5-dimethyl-1-pyrroline-N-oxide as a spin-trap for quantification of hydroxyl radicals in processes based on Fenton reaction

Abstract: Fenton reaction was used to produce hydroxyl radicals under conditions similar to AOPs with 5,5-dimethyl-1-pyrroline- N -oxide (DMPO) as a spin trap agent in electron paramagnetic resonance (EPR) analysis. A theoretical kinetics model was developed to determine conditions under which the spin-adduct DMPO-OH is not further oxidized by Fe 3+ and excessive radicals, so that hydroxyl radicals concentration could be accurately inferred. Experiments were designed based upon the model and H 2 O 2 and Fe 2+ concentrations were varied from 1 to 100 mM and from 0.1 to 10 mM, respectively, with a constant H 2 O 2 : Fe 2+ ratio of 10:1. Results confirmed that DMPO concentration should be at least 20 times higher than the concentration of H 2 O 2 and 200 times higher than iron concentration to produce stable DMPO-OH EPR signal. When DMPO: H 2 O 2 ratio varied from 1 to 10, DMPO-OH could generate intermediates and be further oxidized leading to the apparition of an additional triplet. This signal was attributed to a paramagnetic dimer: its structure and a formation mechanism were proposed. Finally, the utilization of sodium sulfite and catalase to terminate Fenton reaction was discussed. Catalase appeared to be compatible with DMPO. However, sodium sulfite should be avoided since it reacted with DMPO-OH to form DMPO-SO 3 .